Safety-catch for electrical circuits



. 2 Sheets-Sheet 1. HAMMER.

SAFETY OATGH FOR ELECTRICAL GIRGUITS.

(No Model.)

Patented Aug. 23, 1887.

IIII mmnmu-mmum (No Model.) I I 2 sheets-shes 2.

. r W. J. HAMMER.

SAFETY GK' I'GH FOR ELEOTRIGAL'GIRCUITS. No. 368.765. v Patented'Aug. 23, 1887.

UNITED STATES PATENT O E QWILLIAM J. HAMMnaor osToN, MASSACHUSETTS, Assieuon roam SELF, AND FRANCIS a, errors, or ORANGE, NEWJERSEY.

SA F ETY-CATCH R 'JELECTR ICAL oi RC mrs.

, sPEcrrmAmoN mag a of Ii'etters retentive. 368,765, dated August 23, ee'r;

' I Application filed'Mareh 25,1887 Serial No. 232,359. (No model.) I

To'aZZ whom, it may concern.-

Be it known that I, WILLIAM JQHAMMER, of

'Bostomin the county of Suifolk and State of Massachusetts, have invented a certain new and useful Improvem'entin Safety-Catches for Electrical Circuits, of which the following is a specification.

My, invention relates to "s'afety-catehes' or fusible strips which are interp'olated in the conductors of"electrical.circuits, and are de signed to fuse and sobreak the circuitupon the passage-of a current ,greater than that which the circuit is intended toconvey.

My object is to so construct these strips that they will not be injuriously affected by the expansion and contraction of the metal due-tochanges in temperature; that effective connections may be made between them and theterminals of harder metal,to which their ends are permanently connected; that they may be readily and conveniently placed. in circuit,

and, generally, to increase the efficiency,economy, and convenience of devices of this character. I f

' The main feature of my invention consists in making a safetycateh strip. of a numberof' wires of .rea'dilyl'usible, metal, preferably an alloy of lead and other. metal, which wires are braided, woven, twisted, or otherwise formed or massed into a strip which has great flexibility and is readily and conveniently 'put into use.- In. this strip the wires preferably ex tend from end to end of the strip.

My invention further consists invarious novel devices and-combinations of devices einplnyfld by me) in accomplishing the above named objects, as hereinafter set forth and claimed." 4

-My inventionisillustrated-in the aecompanying drawings, in which* Y Figures 1 and 2 are views of simple forms of safety-catches embodying my invention. Fig.

. 3. is a view showing the manner iii-which a safety-catch maybe placed in the circuit; Fig.

4, a viewshow'ing a safety-catch arranged for" greater flexibility and to economize space;

1 Fig. 5, arview showing another way of attach ing the co )er'termin'als to the fusible strip;

Fig. ,6," an enlarged'view of a portion of one of the strips, showingthe way in which it may be made; Fig. 7,3. viewshowing another formlof terminal; Fig. S, a view of-a hollow braided striprFig. 9, a view of a modified form of my invention; Fig. 10, a view of a double safety cateh for additional flexibility,

or otherwise woven or. formed into a fiat strip i of matting. A portion of such a braided flat strip is shown in Fig. ,6. The wires are thus Ibra'ided or woven together, preferably-by suitable machine, in any well-known manner.

13 B are lugs or terminal plates of copper. AS shown in Fig. 1, these plates have upwardlyextending shoulders-and in the edge of each s a slot, a. In these slots the ends of the f usible strips are placed and secured bysoldering,

the strip being bent or curved, as shown, so

that it ma be free to expand and contract nn der variations of temperature without danger of injury to the strip or its connections.

Fig. 2 shows straight terminals 0 G, and the braided strip A, extending straight between them, being secured, as before, in the slots c a in the edge's'of the'terminals.

' Fig. 3 shows the manner of placing these 'safet-yi-eatches in circuit. 1) D represent plates forming terminals of a broken conductor of circuit, and each. provided with a binding. screw, E, as usual; H'eretofore in putting safety-catches in circuit, especially in catch boxes of the Edison underground system, while the current is on there'has been danger of a shock or of burning thehand of theoperator, because it was necessary first to secure one terininal by the binding-screw and then to swing the strip around and bring the other into place and secureit. parts the diillculty mentioned occurs; By reasonof the flexibility of my safety-catch, however, it may be grasped in the middle by a pair of iusulating-nippers, as represented by F, the strip being bent between the nippers, and its terminals then allowed to slide out under the bindingscrews,which may then be screwed down one at. a time upon the terminals.

In Fig. 4 whereby its flexibility or expansib'ility is in lcreased and the space taken up lessened.

In the form shown in Fig. 5 the fusible strip A has straightends, and in each end is sawed In this handling of the metal I thefusible'strip Ads given a twist I06 or cut a slot, 1), in which the thin copper terniinal plates, G, are placed and soldered, instead of inserting the strip in the slotted terminals, as in the preferred form.

The arrangement shown in Fig. 7 is designed to give greater conducting area to the connections between the terminals of the safety-eaten and those of the conductors. The copper terniinals II are crimped or bent,'as shown, and the conductor terminals consist each of a corrugated base, (I, fitting the crimps of the safetycatch terminal, and a corrugated'cover, v, fitting over it, the whole being secured together by screws passed through the screw-holes f.

In Fig. 8 the safety-catch is a hollow tube, I, of braided wires, which may be formed in the well -understood manner of braiding or weaving in this form, Upon each end of this tube I place a sheathing of copper, g. (Shown in section in Fig. 8.) With this form I may employ the kind of connection set forth in my application filed February 16, 1887, Serial No. 227 ,7 7 5-that is to say, the coppencovere'd end of the safety-catch is inserted in the tapering screw-threaded split sleeve 71, and the nut i is screwed up upon this sleeve, so as to make a secure and firm connection. This kind of connection may also be made with a safetycatch, such as in Fig. 9, formed as a rope, K, of wires twisted together with copper-sheathedends.

Fig. 10 shows a safety-catch composed of two braided strips placed together and bent out oppositely at their middles, so as to give greater expansibility and increased radiatingsurface. These are shown as inserted in slots and secured therein by screws in the terminal plates 70 k. They may, however, be soldered, or solder may be used in addition to the screws. The terminals of this figure are different from those shown in the other figures, but arcof a form sometimes used.

I wouldinen'tion that in those forms of my invention in which solder is employed to se cure the strip to its terminals, I may instead, or in addition, electr'oplatc these parts to gether.

In the arrangement using two superimposed strips the copper terminal may be readily inserted and soldered or plated between the ends of these strips, making a connection similar to that of Fig. 5.

Fig. 11 illustrates a convenient method 'of making the terminals, such as those of Fig. 1.

A flat strip of copper, perforated at Z, may be bent over into the form shown,'and the horizontal parts as may then be stamped together, whereby the terminal with an opening for the binding-screw and a slot or opening for the safety-stripis formed.

In all the forms of my invention employing flat terminal plates I have shown suchplates as made with rounded corners. This is'a fea' ture of my invention, such plates havingbeen made heretofore with squared or rectangular corners. Theseareinconvenient,sinceinturn- I ing the safetyeatch, after onetcrmin'al is-ccnnected, to bring the other into position, the squared corners occupy a great deal of space and, especially in a narrow safety-catch box, come into contact with other parts, and may produce aground or a short circuit. The round corners,howcvcr, do not project like the square ones, so that this difficulty does not occur. What I. claim is- I I 1. A flexible safetycatch consisting of a number ,of fusible Wires braided, woven, or

twisted together, substantially as set forth.

2. A flexible safetycatch consisting of a number of fusible wires braided, woven, or twisted-togethcrin such manner that all the wires extend from end to end of the safetycatch, substantially as set forth.

3. A flexible safety-catch consisting of a number of fusible wires braided or woven into a flat strip, substantially as set forth.

4. A flexible safety-catch consisting of a number of fusible wires braided, woven, or twisted together and secured to end plates of harder metal, substantially as set forth.

5. A flexible safety-catch consisting of a number of fusible wires braided orwoven into a fiat strip and secured to terminal plates of harder metal, substantially as set forth.

6. A fusible safety-catch consisting of a number of fusible wires braided or woven into WM. J. HAllIMER.

Witnesses:

0. It. WoLco'r'r, It. I. Goprnnr.

of a

IOC

It is hereby certified tint-t Letters Patent No. 368,765, granted August 23, 1887, upon the application of VVillitnn J. .Hnnnner, of Boston, Massachusetts, for an improvement in Safety Catches for Electrical Circuits, was erroneously issued to Francis R. Upton as assignee of the entire interest, that the said- Letters Patent should have been issued to seid William J. Hammer and Francis R. Upton, jointly, Stlld Upton being the assignee of one-half interest only in said invention; and that the said Letters Patent should be read with this correction therein that the same may conform to the recorder the case in the Patent Office.

Signed, c0untersigned, an(1 sealedthis 30th day of August, A. D. 1587. V

D. L. HAWKINS, Acting Secretmy of the Interior.

[SEAL] Countersigned:

BENTON J. HALL,

Commissioner of Patents.

Correction in Letters'Patent No. 368,765.

It is hefebyeertified that Letters Patent No. 368,765, granted August 23, 1887, upon the application of William J. Hzunmer, of Boston, lrlassachusetts, for an improvement I as assignee of the entire interest, that the snhi Letters Patent should have been issued to seid' lVt'lliani J. Hammer and Fraowis R. Upton, jointly, suiil Upton being the assignee of 0ne-half interest only in said invention; and that the said Letters Patent should be read with this eorreetion therein that the seine may conform to the recorder the case in the Patent Office. v Signed, countersignetl, and sealed this 30th day of August, A. D. 1887.

1). L. HAWKINS, Acting See-retcwy of the Interior.

Counteraigu ed BENTON J. HALL,

OOmmiss-ionefof Patents.

in Safety Catches for Electrical Circuits, \vns erroneously issued to Francis R. Upton 

